Make the Dye class more flexible and fix an issue in it

After the last change, it could go over the end of the colors array.

Reviewed-by: Chuck Miller
Reviewed-by: Freeyorp

2 files changed, 68 insertions, 23 deletions

diff --git a/src/resources/dye.cpp b/src/resources/dye.cpp
index 85a87aa4..c0120bad 100644
--- a/src/resources/dye.cpp
+++ b/src/resources/dye.cpp
@@ -23,6 +23,7 @@
 
 #include "log.h"
 
+#include <math.h>
 #include <sstream>
 
 DyePalette::DyePalette(const std::string &description)
@@ -89,29 +90,25 @@ void DyePalette::addLastColor(const int color[3])
 
 void DyePalette::getColor(int intensity, int color[3]) const
 {
-    if (mColors.size() == 0)
-        return;
-
-    Color c0 = mColors[0];
-
-    // Short circuit for black and single-color palettes
-    if (intensity == 0 || mColors.size() == 1)
+    if (intensity == 0)
     {
-        color[0] = c0.value[0];
-        color[1] = c0.value[1];
-        color[2] = c0.value[2];
+        color[0] = 0;
+        color[1] = 0;
+        color[2] = 0;
+        return;
     }
 
-    int last = mColors.size() - 1;
+    int last = mColors.size();
+    if (last == 0) return;
 
     int i = intensity * last / 255;
     int t = intensity * last % 255;
 
     int j = t != 0 ? i : i - 1;
     // Get the exact color if any, the next color otherwise.
-    int r2 = mColors[j + 1].value[0],
-        g2 = mColors[j + 1].value[1],
-        b2 = mColors[j + 1].value[2];
+    int r2 = mColors[j].value[0],
+        g2 = mColors[j].value[1],
+        b2 = mColors[j].value[2];
 
     if (t == 0)
     {
@@ -122,13 +119,13 @@ void DyePalette::getColor(int intensity, int color[3]) const
         return;
     }
 
-    // Get the previous color.
-    int r1 = c0.value[0], g1 = c0.value[1], b1 = c0.value[2];
+    // Get the previous color. First color is implicitly black.
+    int r1 = 0, g1 = 0, b1 = 0;
     if (i > 0)
     {
-        r1 = mColors[i].value[0];
-        g1 = mColors[i].value[1];
-        b1 = mColors[i].value[2];
+        r1 = mColors[i - 1].value[0];
+        g1 = mColors[i - 1].value[1];
+        b1 = mColors[i - 1].value[2];
     }
 
     // Perform a linear interpolation.
@@ -137,10 +134,53 @@ void DyePalette::getColor(int intensity, int color[3]) const
     color[2] = ((255 - t) * b1 + t * b2) / 255;
 }
 
-Dye::Dye(const std::string &description)
+void DyePalette::getColor(double intensity, int color[3]) const
 {
-    static const int black[3] = {0, 0, 0};
+    // Nothing to do here
+    if (mColors.size() == 0)
+        return;
+
+    // Force range
+    if (intensity > 1.0)
+        intensity = 1.0;
+    else if (intensity < 0.0)
+        intensity = 0.0;
+
+    // Scale up
+    intensity = intensity * (mColors.size() - 1);
 
+    // Color indices
+    int i = (int) floor(intensity);
+    int j = (int) ceil(intensity);
+
+    if (i == j)
+    {
+        // Exact color.
+        color[0] = mColors[i].value[0];
+        color[1] = mColors[i].value[1];
+        color[2] = mColors[i].value[2];
+        return;
+    }
+
+    intensity -= i;
+    double rest = 1 - intensity;
+
+    // Get the colors
+    int r1 = mColors[i].value[0],
+        g1 = mColors[i].value[1],
+        b1 = mColors[i].value[2],
+        r2 = mColors[j].value[0],
+        g2 = mColors[j].value[1],
+        b2 = mColors[j].value[2];
+
+    // Perform the interpolation.
+    color[0] = (rest * r1 + intensity * r2);
+    color[1] = (rest * g1 + intensity * g2);
+    color[2] = (rest * b1 + intensity * b2);
+}
+
+Dye::Dye(const std::string &description)
+{
     for (int i = 0; i < 7; ++i)
         mDyePalettes[i] = 0;
 
@@ -179,7 +219,6 @@ Dye::Dye(const std::string &description)
         }
         mDyePalettes[i] = new DyePalette(description.substr(pos + 2,
                                                             next_pos - pos - 2));
-        mDyePalettes[i]->addFirstColor(black); // First color is black
         ++next_pos;
     }
     while (next_pos < length);
diff --git a/src/resources/dye.h b/src/resources/dye.h
index 51d5d65c..e05f2d5e 100644
--- a/src/resources/dye.h
+++ b/src/resources/dye.h
@@ -44,10 +44,16 @@ class DyePalette
         void addLastColor(const int color[3]);
 
         /**
-         * Gets a pixel color depending on its intensity.
+         * Gets a pixel color depending on its intensity. First color is
+         * implicitly black (0, 0, 0).
          */
         void getColor(int intensity, int color[3]) const;
 
+        /**
+         * Gets a pixel color depending on its intensity.
+         */
+        void getColor(double intensity, int color[3]) const;
+
     private:
 
         struct Color { unsigned char value[3]; };